<meta charset="utf-8">
(#) Using left/right instead of start/end attributes

!!! WARNING: Using left/right instead of start/end attributes
   This is a warning.

Id
:   `RtlHardcoded`
Summary
:   Using left/right instead of start/end attributes
Severity
:   Warning
Category
:   Internationalization: Bidirectional Text
Platform
:   Android
Vendor
:   Android Open Source Project
Feedback
:   https://issuetracker.google.com/issues/new?component=192708
Since
:   Initial
Affects
:   Kotlin and Java files, manifest files and resource files
Editing
:   This check runs on the fly in the IDE editor
Implementation
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/RtlDetector.java)
Tests
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/RtlDetectorTest.java)
Copyright Year
:   2017

Using `Gravity#LEFT` and `Gravity#RIGHT` can lead to problems when a
layout is rendered in locales where text flows from right to left. Use
`Gravity#START` and `Gravity#END` instead. Similarly, in XML `gravity`
and `layout_gravity` attributes, use `start` rather than `left`.

For XML attributes such as paddingLeft and `layout_marginLeft`, use
`paddingStart` and `layout_marginStart`. **NOTE**: If your
`minSdkVersion` is less than 17, you should add **both** the older
left/right attributes **as well as** the new start/end attributes. On
older platforms, where RTL is not supported and the start/end attributes
are unknown and therefore ignored, you need the older left/right
attributes. There is a separate lint check which catches that type of
error.

(Note: For `Gravity#LEFT` and `Gravity#START`, you can use these
constants even when targeting older platforms, because the `start`
bitmask is a superset of the `left` bitmask. Therefore, you can use
`gravity="start"` rather than `gravity="left|start"`.)

!!! Tip
   This lint check has an associated quickfix available in the IDE.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
res/layout/rtl.xml:14:Warning: Use "start" instead of "left" to ensure
correct behavior in right-to-left locales [RtlHardcoded]
    android:layout_gravity="left"
                            ----
res/layout/rtl.xml:22:Warning: Use "end" instead of "right" to ensure
correct behavior in right-to-left locales [RtlHardcoded]
    android:layout_gravity="right"
                            -----
res/layout/rtl.xml:30:Warning: Use "end" instead of "right" to ensure
correct behavior in right-to-left locales [RtlHardcoded]
    android:gravity="right"
                     -----
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here are the relevant source files:

`src/AndroidManifest.xml`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers
&lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="test.rtl"&gt;
    &lt;uses-sdk android:minSdkVersion="5" android:targetSdkVersion="17" /&gt;
&lt;/manifest&gt;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`res/layout/rtl.xml`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers
&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:ignore="HardcodedText" &gt;

    &lt;!-- Warn: Use start instead of left --&gt;

    &lt;Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="left"
        android:text="Button" /&gt;

    &lt;!-- Warn: Use end instead of right with layout_gravity --&gt;

    &lt;Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right"
        android:text="Button" /&gt;

    &lt;!-- Warn: Use end instead of right with gravity --&gt;

    &lt;TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="right"
        android:text="TextView" /&gt;

    &lt;!-- OK: No warning --&gt;

    &lt;Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="start"
        android:text="Button" /&gt;

    &lt;!-- OK: No warning --&gt;

    &lt;Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end"
        android:text="Button" /&gt;

    &lt;!-- OK: No warning --&gt;

    &lt;TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="end"
        android:text="TextView" /&gt;

    &lt;!-- OK: Suppressed --&gt;

    &lt;Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right"
        android:text="Button"
        tools:ignore="RtlHardcoded" /&gt;

&lt;/LinearLayout&gt;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/RtlDetectorTest.java)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `RtlDetector.testTarget17WithRtl`.
To report a problem with this extracted sample, visit
https://issuetracker.google.com/issues/new?component=192708.

(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Adding the suppression attribute `tools:ignore="RtlHardcoded"` on
  the problematic XML element (or one of its enclosing elements). You
  may also need to add the following namespace declaration on the root
  element in the XML file if it's not already there:
  `xmlns:tools="http://schemas.android.com/tools"`.

* Using a suppression annotation like this on the enclosing
  element:

  ```kt
  // Kotlin
  @Suppress("RtlHardcoded")
  fun method() {
     problematicStatement()
  }
  ```

  or

  ```java
  // Java
  @SuppressWarnings("RtlHardcoded")
  void method() {
     problematicStatement();
  }
  ```

* Using a suppression comment like this on the line above:

  ```kt
  //noinspection RtlHardcoded
  problematicStatement()
  ```

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="RtlHardcoded" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'RtlHardcoded'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore RtlHardcoded ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

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